Flavour characterization of fresh and processed pennywort (Centella asiatica L.) juices
Pronprapa Wongfhuna, Michael H. Gordonb and Arunee Apichartsrangkoona
a
Department of Food Science and Technology, Chiangmai University, Thailand
b
Department of Food Biosciences, University of Reading, UK
The flavour characteristics of fresh and processed pennywort juices treated by
pasteurization, sterilization and high pressure processing (HPP) were investigated by using
solid-phase micro-extraction combined with gas chromatography-mass spectrometry.
Sesquiterpene hydrocarbons comprised the major class of volatile components present and the
juices had a characteristic smell due to the presence of volatile compounds including βcaryophyllene, humulene, E-β-farnesene, α-copaene, alloaromadendrene and β-elemene. All
processing operations caused a reduction in the total volatile concentration, but HPP caused
more volatile acyclic alcohols, aldehydes and oxygenated monoterpenoids to be retained than
pasteurization and sterilization. Ketones were not present in fresh pennywort juice, but 2butanone and 3-nonen-2-one were generated in all processed juices, and 2-nonanone and 2hexanone were present in pasteurized and sterilized juices. Other chemical changes including
isomerization were also reduced by HPP compared to pasteurization, and sterilization.
Keywords: Aroma; Flavour; Headspace volatiles; Centella asiatica; High pressure
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INTRODUCTION
Asiatic pennywort (C.asiatica), also known as gotu kola and pegapa is one of the
herbs grown in Thailand and other Asian countries that is claimed to possess various
physiological effects. It has been used for hundreds of years as an anti-inflammatory and a
treatment for leprosy and syphilis. It has been included in Thai traditional recipes as a poultice
for wound healing (Farnsworth & Buryapraphatsara, 1992) and is commonly used as a
vegetable and tonic (Pramongkit, 1995). Moreover, it has been reported that wound and ulcer
healing are enhanced by its action in promoting fibroblast proliferation and collagen synthesis
(Maquart, Bellon, Gillery, Wegrowski & Borel, 1990).
Non-thermal methods for juice processing including high pressure have been applied
more widely during the past few years. High pressure processing (HPP) is frequently applied
in juice processing because it inactivates microorganisms with minimal damage to heat
sensitive compounds. This method is capable of maintaining freshness and nutritive value
(flavour, colour, vitamin content, biologically active components, etc.). The European
Commission has included products processed by high pressure in the group of novel foods
regulated by the Novel Foods Legislation.
Herbal plants have commanded special attention due to their value. However, quality
control of raw herbs and their products is essential to ensure quality, safety and efficacy. The
flavour of herbal plants is due to essential oils which are complex mixtures mainly containing
volatile compounds. The most volatile are mono (C10) and sesquiterpenoids (C15) that
represent the major components of essential oils. Monoterpenoids may have acyclic,
monocyclic and bicyclic structures, and occur in nature as hydrocarbons, alcohols, ketones,
aldehydes, ethers, etc. Many literature reports describe the importance of monoterpenoids for
the flavour of foods (Perez-Cacho and Rouseff, 2008). However, monoterpenoid chemistry is
complex, since they are distinguished by structural characteristics, including the presence of
endocyclic and exocyclic carbon–carbon double bonds, which present steric limitations and
contribute distinct reactivities; functionalized and substituted skeletons; the presence of highly
tensioned rings, and the possibility of bicyclic ring rearrangements.
Chou (2005) identified nineteen compounds in the essential oil from C.asiatica in
Taiwan as linalool, p-meth-1-en-8-ol, copaene, elemene, sesquiphellandrene, caryophyllene,
thjosene, cadinene, acoradien, humulene, alloaromadendrene, farnesene, selinene, 1,5,5,81
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tetramethyl-1,2-oxabicyclo [9,1,0] dodeca-3,7-diene, eudesmene, cuparene, caryophyllene
oxide, phytol and hexahydrofarnesylacetone. Ali (2007) reported 23 compounds in this plant
from Malaysia including α-pinene (1.2%), germacrene D (1.6%), (+)-cyclosativene (2.3%),
β-farnesene (4.8%), β-cubebene (17%), α-caryophyllene (17%), α-humulene (22%), γmurolene (22%) and various components with concentrations less than 1% including βpinene, m-cymene, D-limonene, β-trans-ocimene, γ-terpinene, 1-bromoallene, β-linalool,
trans-3-nonen-2-one, terpinen-4-ol, ο-menth-8-ene,4-isopropylidene-1-vinyl-, α-cubebene, ndecyl acetate, β-cedrene, δ-cadinene and caryophyllene oxide. Oyedeji & Afolayan (2005)
also reported that the essential oil extracted from C.asiatica grown in South Africa contained
11 monoterpenoid hydrocarbons (20.20%), 9 oxygenated monoterpenoids (5.46%), 14
sesquiterpenoid hydrocarbons (68.89%), 5 oxygenated sesquiterpenoids (3.90%) and 1 sulfide
sesquiterpenoid (0.76%). Components present included sesquiterpenoid hydrocarbons
including α-humulene (21.06%), β-caryophyllene (19.08%), bicyclogermacrene (11.22%),
germacrene B (6.29%) and myrcene (6.55%). Other reports included trans-β-farnesene and
germacrene D as prominent constituents of the essential oil.
The effect of heat treatment and HPP on pennywort juice flavour production has not
been reported. In the present studies, we have analyzed fresh and processed pennywort juice
aroma by gas chromatography-mass spectrometry (GC-MS) using solid-phase microextraction (SPME).
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4. GC-MS analysis
Analysis was carried out with a Hewlett-Packard 5890 series П GC connected to a
5972 series MS and a 60 m VF-5 ms capillary column (i.d. 0.25 mm, 0.25 µm film thickness,
Varian). The injector port was in splitless mode, and split flow was programmed to turn on
after 0.5 min. The temperature of the injector was 250 ºC. The oven temperature was kept at
MATERIALS AND METHODS
1. Raw material and preparation
The plant sample was freshly harvested, with commercial maturity (2-4 months)
obtained from high land, Chiangmai, Thailand. Upon arrival at the laboratory, the sample was
washed with running tap water to remove debris and damaged portions. The leaves and
petioles of pennywort were stripped from the plant and extracted with water (1:1 w/v) by
grinding at room temperature for 15 min. This juice was filled in double layer of LDPE
Stomacher pouch (Seward Limited, UK.) before HPP and filled in retort pouch
(PET/nylon/aluminium/PP) (Royal Can Industries Co., Ltd, Thailand) before pasteurization
and sterilization. The samples were subjected to pasteurization (90 ºC for 3 min), sterilization
(121 ºC for 4 min) and HPP (400 MPa for 20 min at < 30 ºC).
2. Chemicals
1, 2-Dichlorobenzene (99% from Sigma-Aldrich Company, Ltd, Poole, UK) was
used as an internal standard (IS) for GC-MS analysis, as this compound was not found in the
pennywort juice.
3. Headspace concentration
The sample (20 ml) was transferred to a 40 ml amber vial which was capped with a
PTFE septum. 1, 2-Dichlorobenzene (10 µl) was added and the vial was incubated for 5 min
at 35ºC, before a 75 µm Supleco SPME fiber Carboxen/Polydimethylsiloxane (PDMS) was
introduced and exposed to the sample headspace for 30 minutes. The SPME fibre was then
inserted into the GC-MS injection port and held for 15 minutes with the adsorbed components
being effectively desorbed. The isolation and GC-MS analysis of volatiles from each sample
of pennywort juice was repeated 4 times.
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50 ºC for 3 min and programmed to increase at 4 ºC min-1. The final temperature was set at
240 ºC and held for 5 min.
Retention times for a series of n-alkanes (C5-C25) were determined in the study by an
analysis under exactly the same conditions, and they were used to calculate the LRI values of
detected compounds.
The relative concentrations of the investigated compounds were calculated by relating
the area of the internal standard to the area of the compound of interest, defined as:
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RESULTS AND DISCUSSION
Flavour of fresh juice
The flavour compounds in fresh and processed pennywort juice treated by heat and
high pressure treatment are shown in Table 1 and Table 2. Fresh juice and high pressure
processed juice contained 40 and 39 volatile components that could be identified,
respectively, whereas pasteurized and sterilized juice contained 39 and 38 volatile compounds
respectively. 29 Components occurred in all the fresh and processed juice samples, although
in some samples only traces of some compounds were detected. Fresh juice was characterized
by a high content of the oxygenated monoterpenes; linalool (335.5 ng/L), geraniol (146.9
ng/L) and β-cyclocitral (42.5 ng/L) and the sesquiterpenoid hydrocarbons β–caryophyllene
(1344.0 ng/L) and humulene (1602.2 ng/L) were present at higher concentrations in the fresh
juice than other volatiles. Chou (2005) and Oyedeji & Afolayan (2005) reported that the main
compounds in the essential oil of pennywort were linalool, copaene, elemene, caryophyllene,
cadinene, humulene, alloaromadendrene, farnesene, selinene, cuparene, caryophyllene oxide,
bicyclogermacrene and myrcene. All these components except for bicyclogermacrene were
detected in fresh juice in this study, and the volatile compounds included 4 alcohols, 6
aldehydes, 4 monoterpenoid hydrocarbons, 3 oxygenated monoterpenoid, 19 sesquiterpenoid
hydrocarbons, 1 oxygenated sesquiterpenoid, 4 miscellaneous compounds (Table 1) as well
as 19 unknown components (data not shown). Forty different varieties of C. asiatica have
been identified throughout the world (de Padua, Bunyapraphatsara & Lemmens, 1999), so
differences in reported volatile components are not surprising.
Relative conc. = [Peak area of particular compound] x IS conc.
Peak area of IS
Statistical analysis. Mean total volatiles were analyzed by ANOVA one-way with a Tukey’s
post-hoc test to assess significant differences between processing methods (p <0.05).
Effects of processing on chemical classes
There is no published information about the effect of heat and HPP treatment on
volatile components of pennywort juice. The total concentration of volatile compounds in
fresh juice was higher than in processed juice (p<0.05) and there was a non-significant trend
in the order sterilized juice > HPP juice > pasteurized juice, respectively. Reductions in the
concentration of acyclic alcohols, aldehydes, oxygenated monoterpenes, sesquiterpene
hydrocarbons, and oxygenated sesquiterpenes were detected after some of the processing
operation, whereas ketones increased significantly (Table 2). Aldehydes and oxygenated
sesquiterpenes were present at higher concentration in fresh juice than in other samples
(p<0.05), monoterpene hydrocarbons were also found in high concentrations but there was no
significant difference between HPP and heat-treated samples (p>0.05). In addition, there was
no significant difference between fresh and HPP juice (p>0.05) in the total content of
alcohols, ketones and oxygenated monoterpenoids. Moreover, there was no significant
difference between HPP and processed juice (p>0.05) in the content of acyclic alcohols,
aldehydes, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated
sesquiterpenes, miscellaneous compounds and total volatiles as shown in Table 2. However,
HPP caused more flavour volatiles in the acyclic alcohols class to be retained, with a trend to
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greater retention of aldehydes and oxygenated monoterpenoids (p>0.05) than pasteurization
and sterilization.
Effects of processing on non-terpenoid compounds
The fresh pennywort juice contained aldehydes including hexanal and 2-nonenal that
were presumably formed by enzymatic oxidation in the plant post-harvest and during
preparation of the juice. (E)-2-Nonenal and hexanal are biosynthesized in plant tissues by
lipoxygenase-mediated lipid oxidation of polyunsaturated fatty acids (Vichi, Guadayol,
Caixach, Lopez-Tamames & Buxaderas, 2007; Hatanaka, 1996), although they may also be
formed by autoxidation. Processing of the juice reduced the concentration of these
components, but hexanal was found in sterilized samples in higher concentrations than in
pasteurized and HPP juice, so some formation of this compound by autoxidation is suspected
under sterilization conditions. Other aldehydes including 2-methyl-propanal, 3-methylbutanal, 2-methyl-butanal, 2, 6-nonadienal and 2-nonenal had decreased or disappeared after
thermal treatment. Aldehydes are known to degrade readily by chemical reactions including
acetal formation which occurs in the presence of alcohols under acid conditions (Jerry, 1992).
Ketones including 2-butanone, 2-nonanone, 5-methyl-2-hexanone and 3-nonen-2-one
were present after processing but not in the fresh juice, with concentrations of 2-nonanone
and 3-nonen-2-one significantly higher in sterilized than in high pressure processed juice
indicating these components were formed due to the high temperatures employed in
sterilization.
Acyclic alcohols including 1-penten-3-ol, 3-methyl-1-butanol, 2-methyl-1-butanol and
hexanol were found in high abundance in fresh and HPP juice. These compounds might be
formed during sample preparation because no action was taken to inactivate enzymes prior to
extraction in this study. Hexanol was detected in the HPP juices. Stone, Hall & Kazeniac
(1975) reported that alcohols (hexanol) are formed in plant tissues by alcohol oxidoreductase
activity on C6 aldehydes (hexanal).
Effects of processing on terpenoid compounds
The class of oxygenated monoterpenes was reduced in concentration by processing
(Table 2). β-Cyclocitral and caryophyllene oxide were found in fresh juice but not in
processed juice. Since these components were amongst the less volatile of the volatile
fraction, it is probable that these components were lost by chemical transformation. It was
clear that these volatile components were retained better by HPP than by pasteurization or
sterilization.
Linalool was the major component of the oxygenated monoterpene class present in
fresh juice, but it was found to be reduced (p<0.05) by the thermal processing of pennywort
juice. Sterilization and pasteurization caused big drops in the concentration of linalool. αTerpineol was not detected in fresh juice but it was formed in low concentrations in high
pressure processed juice. This component is considered to be desirable in many fruits,
whereas in others it is perceived as an off-flavour (terpentine-like) (Dung, Moi, Nam, Cu &
Leclercq, 1995). It is known to be formed in citrus juices from limonene and linalool by acidcatalyzed reactions (Haleva-Toledom Naim, Zehavi & Rouseff, 1999). Rui, Xiaoyan,
Taixiang & Guanjjian (2007) reported isomerisation of linalool and dehydration to
monoterpenes shown as Figure 1. Geraniol was not detected in sterilized pennywort juice, but
was present in the fresh juice and in samples processed by other methods. This is also
susceptible to dehydration under acid conditions (Jerry, 1992).
In this study, terpinolene and α-terpinene were found in heat-treated samples but
myrcene, α-pinene and β-pinene were found in all samples. In contrast, limonene was present
only at trace levels in fresh juice, which is in agreement with the findings of Chou (2005),
although Ali (2007) did detect D-limonene in pennywort juice. Our studies show that γterpenene, which contributes bitter flavours, was found in higher concentration in processed
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samples. Myrcene, which was described as contributing pine odour to Piatacia lenticus (Seo
& Beak, 2005) was present at a high concentration in all samples. β-Pinene is a compound
with a plastic and pine-like aroma present in Piper nigrum, Pistacia lenticus, Argyranthemum
adauctum, Sideritis bigerana (Zheng, Kim, Kim & Lee, 2005), water dropwort (Seo & Beak,
2005), carrot (Kreutzmann, Thybo, Edelenbos & Christensen, 2008) and it is also important
for the overall aroma of omija leaves (Zheng, Kim, Kim & Lee, 2005). It was found at higher
concentration in fresh pennywort juice than in processed samples (p<0.05).
The sesquiterpene class, including β-caryophyllene, humulene, E-β-farnesene, αcopaene, alloaromadendrene and β-elemene was the major class of volatiles present in
pennywort juice. β-Caryophyllene and (Z, E)-β-farnesene contributed to the woody note in
water dropwort (Seo & Beak, 2005). All samples contained germacrene D but only trace
levels were present in fresh and HPP juice. It has been reported as the predominant
sesquiterpene in various essential oils of Pinus canariensis, P. pauce and P. pinaster and as
the major volatile compound of omija leaves (Zheng, Kim, Kim & Lee, 2005). β-Elemene
was found at a higher concentration in fresh pennywort juice than in other samples (p<0.05).
It has also been reported in omija fruits, Murraya koenigii, Stachys swainsonii spp
melangavica and it was identified as the main component of basil oil and omija leaves
(Zheng, Kim, Kim & Lee, 2005).
The oxygenated sesquiterpene, caryophyllene oxide was only detected in the fresh
juice. Chou (2005) and Ali (2007) also detected caryophyllene oxide in pennywort.
Temperature and pressure are important parameters in determining the juice aroma
which may be modified by thermal and high pressure induced reactions. Some of the
compounds detected in the processed juice including calamenene have not been reported
previously in fresh pennywort juice. However, the effects of processing on volatile
compounds in pennywort juice have not been reported previously.
Benefits of HPP Processing compared to Thermal Processing Methods
The main justification for HPP of foods is that more valuable constituents, for
example, aroma compounds and vitamins (Gotz and Weisser, 2002), are retained than in
thermally processed foods. In this study, many compounds were conserved better by HPP
treatment including linalool, geraniol, α-copaene, alloaromadendrene, β-selinene, α-selinene
and cuparene. Some compounds were present in fresh juice but were lost during HPP
including 2, 6-nonadienal, 2-nonenal, β-cyclocitral, γ-cadinene, caryophyllene oxide and 4
unknown compounds (data not shown). In contrast, some of the identified compounds were
not present in fresh juice but were found in HPP juice including γ-terpinene, 2-butanone, 3nonen-2-one, α-terpineol, tetrahydrofuran and 3 unknown compounds. These findings indicate
that HPP can induce chemical changes which generate new compounds from components of
the original juice.
Several compounds were detected in heat-treated juice but were not found in fresh and
HPP juice, including α-terpinene and α-ylangene. Some compounds were only detected in
processed juice including hexanol, α-terpinene, γ-terpinene, terpiolene, ketones, α-terpineol,
α-ylangene, bicyclogermacrene, γ-cadinene, tetrahydrofuran and 13 unknown compounds.
However, some compounds which have been previously reported as components of fresh
pennywort juice including bicyclogermacrene, which was present at 11.2% of the essential oil
isolated by Oyedeji & Afolayan, 2005 , were not detected in the current study.
Hendrickx, Ludikhuyze, Van den Broeck & Weemaes (1998) reported that high
pressure process-induced enzyme activation and inactivation are relevant to food quality;
enzyme activation can arise from pressure-induced decompartmentalization (Butz, Koller,
Tauscher & Wolf , 1994 and Gomes & Ledward, 1996). However, the aldehydes e.g. hexanal,
which may be formed by enzymatic processes were at low concentrations after high pressure
processing, so there is no evidence for this phenomenon in this study.
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Yu & Chiang (1986) reported that pasteurization (75 ºC for 40 s) of passion fruit juice
caused about 45% loss of flavor compounds based on total volatiles. For this study, there was
a significant reduction in volatiles between fresh and high pressure and pasteurized samples
(p<0.05) and a non-significant trend for a reduction in total volatiles between fresh and
sterilized juice (p>0.05) (Table 2). Carelli, Crapiste & Lozano. (1991) considered the effect of
temperature on the release of aroma compounds in apple juice, and it was found that raising
the temperature from 25 to 65 ºC caused an increase in interactions between aroma
compounds (pentyl acetate, hexanal, hexanol) and macromolecules in apple juice (fructose).
Jouquand, Ducruet & Giampaoli (2004) also reported that aroma compounds bind to
macromolecules by hydrophobic interactions and this effect was enhanced by heat treatment,
which caused the lower release of aroma compounds in pasteurized orange juice. Decrease in
juice flavour on processing may be caused by these interactions or by evaporation or thermal
degradation (Su & Wiley, 1998).
γ 2- Cadinene was not detected in the fresh juice and in the high pressure processed
samples but was present in the thermally treated samples. However, γ-cadinene was present in
the fresh juice but may have isomerised to the 2-isomer on heating.
In conclusion, it appears that several chemical changes occurred as well as loss of
volatiles during the heating processes of pasteurization and sterilization. Our data suggest that
thermal and HPP treatment can cause chemical changes in some plant components eg by
dehydration or isomerisation reactions. Although the total volatile concentration in sterilized
juice was higher than in juice processed by other methods (p>0.05), some volatile
components that were not present in the fresh juice were formed at high levels in the sterilized
juice eg. γ-terpinene, ketones, γ 2-cadinene and germacrene D. This indicates that high pressure
treatment could maintain the flavour better than pasteurization and sterilization. The detection
of ketones is a good marker that processing has been applied to the juice.
ACKNOWLEDGMENT
The authors thank Mr. Andrew Dodson, Dr. J. Stephen Elmore and Professor Donald
Mottram, Department of Food Biosciences, University of Reading, UK. for assistance in the
GC- MS analysis and the Ministry of Science and Technology, Thailand for the generous
financial support through the National Science and Technology Development Agency
(NSTDA) grant.
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List of figures:
Figure 1. Isomerisation of linalool and dehydration to monoterpenes (Rui Xiaoyan, Taixiang
& Guanjjian, 2007)
8
Table 1. Concentrations of volatile compounds identified in fresh and processed pennywort
juices
Mean concentration ± sd (ng/L) A
Compounds (m/z)
Fresh
Acyclic alcohols
1-penten-3-ol
123.5±54.0 a
1-butanol, 3-methyl- 29, 37, 39,
42, 51, 53, 55, 57, 60, 70, 77
19.7±23.2 ns
1-butanol, 2-methyl- 39, 41, 43,
45, 53, 55, 57, 59, 70
43.5±29.5 a
Hexanol
nf b
Aldehydes
Propanal, 2-methyl- 29, 37, 39,
41, 43, 45, 50, 53, 55, 57, 59,
72, 74
97.5±85.6 a
Butanal, 3-methyl- 29, 37, 39,
41, 44, 50, 53, 55, 58, 71, 86
79.5±38.0 a
Butanal, 2-methyl- 41, 57, 71, 86 187.1±105.1 a
Hexanal
142.4±68.2 a
2, 6-Nonadienal
88.2±68.6 a
2-Nonenal
72.7±55.0 a
Ketone
2-Butanone
nf ns
2-Nonanone
nf b
2-Hexanone, 5-methyl- 43, 53,
58, 71
nf b
3-Nonen-2-one
nf b
Monoterpenes hydrocarbon
α-Pinene
92.5±39.1 a
β-Pinene
108.2±43.5 a
Myrcene
167.2±77.4 ns
α-Terpinene
nf ns
Limonene
trace ns
γ- Terpinene
nf b
Terpinolene
nf b
Oxygenated monoterpenoids
Linalool
335.5±148.6a
α-Terpineol
nf ns
β-Cyclocitral
42.5±30.4 a
Geraniol
146.9±74.6 a
Sesquiterpene hydrocarbons
α-Cubebene
147.3±57.5 ns
α-Ylangene
nf b
α-Copaene
537.6±221.1ns
β-Elemene
248.6±107.5 a
β-Caryophyllene
1344.0±1049.2 ns
β- Copaene 41, 55, 69, 91, 105,
119, 133, 161, 204
16.6±14.6 ns
(E)- β –Farnesene
551.8±200.5 ns
Humulene
1602.2±668.7 ns
Alloaromadendrene
258.3±105.0 a
δ-Cadinene
29.7±8.3 ns
γ 2-Cadinene
nf b
γ-Curcumene
trace ns
Germacrene D
trace b
Valencene
146.0±102.0 ns
β-Selinene
34.9±27.3 ns
α-Muurolene
50.5±42.4 ns
Bicyclogermacrene
nf b
α-Selinene
130.2±68.1 a
Cuparene
192.8±81.1 a
γ-Cadinene
96.5±30.8 ab
δ-Cadinene (armoise-Maroc)
163.1±50.7 ns
Calamenene
101.7±34.1 ns
Oxygenated Sesquiterpene
Caryophyllene oxide
37.7±28.8 a
Miscellaneous
Dimethyl sulfide 29, 35, 43, 45,
47, 49, 58, 62, 64
840.9±429.6 a
Tetrahydrofuran
nf b
Furan, 2-pentyl- 53, 81, 109, 138 87.9±23.7 a
1-Methyl-3-isopropylbenzene
51, 57, 65, 77, 91, 103, 115,
119, 134
138.3±53.9 ns
5-ethyl-1-formylcyclopentene 39,
63, 67, 77, 81, 91, 95, 109, 124 64.7±49.9 a
HPP
method of
identificationB
LRIC
Pasteurization
Sterilization
28.1±21.4 b
nf b
nf b
6.2±8.7
nf
nf
12.2±10.4 ab
20.1±16.2 a
nf b
nf b
nf b
nf b
35.2±25.2 ab
trace b
trace b
26.2±20.0 ab
62.5±47.6 ab
8.6±9.9 b
nf b
nf b
nf b
8.1±6.3 b
53.2±27.8 ab
nf b
nf b
nf b
-b
90.4±48.9 ab
nf b
nf b
se
se
MS+LRI
msO
MS+LRI
659
669
805
1162
1168
12.8±9.0
nf b
18.5±18.3
21.2±10.7 ab
11.1±9.5
58.8±32.6 a
MS+LRI
MS+LRI
601
1095
nf b
16.8±27.6 b
30.9±22.6 a
123.5±72.5 ab
14.5±12.1 ab
185.7±98.2 a
24.7±22.8 b
29.1±26.5 b
86.8±110.2
nf
9.3±15.8
13.0±22.3 ab
nf b
20.1±11.3 b
21.9±16.4 b
72.2±61.6
nf
15.3±11.1
65.1±50.2 ab
25.5±19.6 a
31.4±23.9 b
36.8±27.1 b
160.6±117.7
15.3±15.3
28.6±18.3
131.9±92.8 a
8.1±7.3 ab
MS+LRI
MS+LRI
MS+LRI
msN
MS+LRI
MS+LRI
msF
940
987
993
1025
1037
1066
1094
208.0±177.4ab
5.4±7.9
nf b
45.7±45.0 b
83.6±48.1b
nf b
22.9±17.1 b
82.0±49.5b
nf b
trace b
MS+LRI
MS+LRI
MS+LRI
MS+LRI
1106
1210
1235
1258
71.7±90.2
nf b
250.6±302.5
78.3±96.3 ab
710.3±864.0
44.7±24.7
6.8±9.0 ab
108.0±54.1
67.9±40.0 b
464.3±252.4
89.8±56.7
17.4±9.7 a
207.4±140.2
111.7±66.3 ab
750.0±449.8
msD
msL
msD
msE
msF
1361
1387
1394
1405
1444
248.5±338.9
685.6±827.7
105.8±134.0 ab
29.0±26.2
nf b
34.8±44.3
trace b
17.2±21.7
52.8±83.2
24.1±32.2
-b
46.7±61.5 ab
65.2±80.5 ab
nf b
72.3±94.8
38.0±42.5
15.7±11.8
520.8±274.6
533.7±292.8
35.0±42.8 b
35.7±38.7
78.3±40.1 a
39.9±18.2
93.7±72.8 ab
68.6±32.0
13.9±9.2
11.6±12.6 ab
17.4±16.7 b
nf b
84.0±46.2 ab
126.7±67.6
65.0±34.5
22.4±12.1
882.2±562.5
777.5±425.3
48.5±41.9 b
34.1±23.7
88.6±57.0 a
64.7±40.3
186.8±118.4 a
75.4±50.5
25.3±27.6
17.0±9.7 a
34.2±24.4 ab
nf b
128.0±84.0 a
209.1±135.7
89.9±57.2
se
msG
msH
msD
msJ
msI
msE
msD
MS+LRI
msE
msL
msD
msK
msM
msD
msD
msJ
1451
1461
1481
1485
1393
1494
1498
1504
1514
1515
1518
1520
1521
1535
1535
1538
1544
nf b
nf b
nf b
190.3±159.7 b
71.5±58.1 a
trace c
187.9±125.5 b
trace b
13.7±12.3 bc
361.1±149.9 ab
-b
34.2±19.9 b
54.3±63.8
91.6±68.1
nf b
nf b
A
MS+LRI
se
se
MS+LRI
se
se
MS+LRI
689
736
741
873
567
1095
1145
msE
1613
se
MS+LRI
se
532
633
995
148.3±95.3
se
1033
nf b
se
1042
Approximate quantities (ng) in headspace from 20 ml of sample were estimated by comparison with 100 ng of 1,2-dichlorobenzene internal
standard, mean values of 3-4 replicates analyses are given; compounds identified below 2 ng are reported as trace; -, less than 0.5 ng; nf, not
9
found. B MS+LRI, mass spectrum and LRI agree with those of authentic compound; ms, mass spectrum agree with spectrum in mass spectral
database or with those reported in previous studies as listed below; se, tentative identification from structure elucidation of mass spectrum.
C
LRI; Liner retention indices on a VF-5MS column
D
Kondjoyan, N. & Berdague, J. (1996)
E
Noueira, P., Bittrich, V., Shepherd, G., Lopes, A. & Marsaioli, A. (2001)
F
Quorn®
G
Priestap, H.A., van Baren, C.M., Lira, P.D.L., Coussio, J.D. & Bandoni, A.L. (2003)
H
Flavornet
I
Kilic, A., Hafizoglu, H., Kollmannsberger, H. & Nitz, S. (2004)
J
Vichi, S., Riu-Aumatell, M., Mora-Pons, M., Guadayol, J.M., Buxaderas, S. & Lopez-Tamames, E. & (2007)
K
Adams, R.P. (1995)
L
Baranauskinene, R., Venshutonis, R.P. & Demyttenaere, J.C.R. (2003)
M
Sacchetti, G., Maietti, S., Muzzoli, M., Scaglianti, M. Manfredini, S., Radice, M. & Bruni, R. (2005)
N
Flamini, G., Cioni, P.L., Morelli, I., Macchia, M. & Ceccarini, L. (2002)
O
Skaltsa, H.D., Demetzos, C., Lazari, D. & Sokoric, M. (2003)
Table 2. Concentrations (ng/L) of volatile product groups
Compound groups
Acyclic alcohols
Aldehydes
Ketones
Monoterpene hydrocarbons
Oxygenated monoterpene
Sesquiterpene hydrocarbons
Oxygenated sesquiterpene
Miscellaneous
Total
Fresh
186.8±54.4 a
665.6±44.7 a
nf b
367.9±69.4 ns
524.9±149.5 a
5651.9±424.9 a
37.7±28.8 a
1634.2±168.6 a
9069.±1898.3 a
Total concentration ± sd (ng/L)
HPP
Pasteurization
66.7±9.5 ab
nf b
132.6±24.4 b
61.4±21.3 b
29.5±8.7 b
194.1±50.3 ab
162.8±30.2
219.9±26.8
259.1±97.6 ab
106.4±39.5 b
b
2530.8±201.1
2431.6±165.2 b
nf b
nf b
435.8±41.3 b
550.6±42.4 b
3617.2±851.5 b
3564.0±821.9 b
Sterilization
nf b
90.4±36.9 b
270.1±81.7 a
412.8±61.0
82.0±41.0 b
3859.8±263.6 ab
nf b
1168.6±77.5 ab
5883.7±1319.9 ab
Total concentration with different letters within a row are significantly different (p<0.05) (Tukey’s), non significantly different (ns),
compounds identified below 0.5 ng are reported as not found (nf).
10
11